U.S. patent number 5,411,483 [Application Number 08/040,373] was granted by the patent office on 1995-05-02 for gas-tight seal accommodating surgical instruments with a wide range of diameters.
This patent grant is currently assigned to Origin Medsystems, Inc.. Invention is credited to Edwin J. Hlavka, Bryan E. Loomas, John P. Lunsford.
United States Patent |
5,411,483 |
Loomas , et al. |
* May 2, 1995 |
Gas-tight seal accommodating surgical instruments with a wide range
of diameters
Abstract
A seal for use in a surgical instrument to provide a gas-tight
seal with an instrument passed through the seal. The seal can form
a gas-tight seal with an instrument having a diameter within a wide
range of diameters. The seal comprises a seal body, an instrument
seal, and a laterally-compliant seal mounting. The seal body
includes a bore through which the instrument is passed. The
instrument seal is made of an elastic material. The instrument seal
extends radially outwards from an instrument port formed in the
instrument seal through which the instrument is passed. The
instrument port is substantially perpendicular to the axis. The
instrument seal also extends axially from the instrument port in
the direction opposite to that in which the instrument is passed
through the instrument port. The laterally-compliant seal mounting
mounts the instrument seal to the seal body, forms a gas-fight seal
between the instrument seal and the seal body, and allows the
instrument seal to move freely laterally in response to lateral
movement of the instrument.
Inventors: |
Loomas; Bryan E. (Santa Clara,
CA), Lunsford; John P. (San Carlos, CA), Hlavka; Edwin
J. (Palo Alto, CA) |
Assignee: |
Origin Medsystems, Inc. (Menlo
Park, CA)
|
[*] Notice: |
The portion of the term of this patent
subsequent to April 18, 2012 has been disclaimed. |
Family
ID: |
26687772 |
Appl.
No.: |
08/040,373 |
Filed: |
March 30, 1993 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
15765 |
Feb 10, 1993 |
|
|
|
|
Current U.S.
Class: |
604/167.06;
604/256 |
Current CPC
Class: |
A61B
17/3462 (20130101); A61M 39/06 (20130101); A61M
39/0613 (20130101); A61B 17/3498 (20130101); A61B
2017/3464 (20130101); A61M 2039/0279 (20130101); A61M
2039/0626 (20130101); A61M 2039/0673 (20130101); A61M
2039/0686 (20130101) |
Current International
Class: |
A61B
17/34 (20060101); A61M 39/02 (20060101); A61M
39/06 (20060101); A61M 005/00 () |
Field of
Search: |
;604/167,256
;251/149.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0051718 |
|
May 1982 |
|
EP |
|
0113520 |
|
Jul 1984 |
|
EP |
|
0312219 |
|
Apr 1989 |
|
EP |
|
1482857 |
|
Aug 1977 |
|
GB |
|
WO93/4717 |
|
Mar 1993 |
|
WO |
|
Primary Examiner: Hirsch; Paul J.
Attorney, Agent or Firm: Hardcastle; Ian Limbach &
Limbach
Parent Case Text
PRIOR APPLICATION
The application is a Continuation-in-Part of prior application Ser.
No. 08/015,765, of inventor Bryan Loomas, filed 10 Feb. 1993.
Claims
I claim:
1. Apparatus for use in a surgical instrument to provide a
gas-tight seal with an instrument passed therethrough, the
instrument having a diameter in a wide range of diameters, the
apparatus comprising:
a seal body including a bore wherethrough the instrument is passed,
the bore defining an axis; and
an instrument seal assembly, including:
a rigid annulus, and
an instrument seal comprising an elastic material, the instrument
seal extending axially and radially outwards from an instrument
port therein to the rigid annulus whereto the instrument seal is
fixedly attached, the instrument being passed through the
instrument port in an insertion direction, the instrument port
being substantially perpendicular to the axis, the instrument seal
extending axially from the instrument port in a direction opposite
to the insertion direction;
the instrument seal assembly being mounted in the seal body, and
forming a gas-tight seal therewith, in a manner that restricts
axial movement of the instrument seal assembly and that allows free
lateral movement of the instrument seal assembly response to
movement of the instrument.
2. The apparatus of claim 1, wherein:
the seal body includes a first internal face opposite a second
internal face, the internal faces being disposed about the bore;
and
the rigid annulus is slidably mounted between the first internal
face and the second internal face.
3. The apparatus of claim 2, additionally comprising a low-friction
coating applied to the instrument seal.
4. The apparatus of claim 2, wherein the rigid annulus includes
first plane face opposite a second plane face, and is mounted in
the seal body with the first plane face opposite the first internal
face of the seal body and the second plane face opposite the second
internal face of the seal body.
5. The apparatus of claim 4, wherein the laterally-compliant seal
mounting means additionally includes:
a first annular wiper attached to the first plane face of the rigid
annulus and contacting the first internal face of the seal body;
and
a second annular wiper attached to the second plane face of the
rigid annulus and contacting the second internal face of the seal
body.
6. The apparatus of claim 5, additionally comprising a low-friction
coating applied to the instrument seal.
7. The apparatus claim 1, wherein the instrument seal additionally
includes
a laterally-compliant annulus disposed between the rigid annulus
and the seal body.
8. The apparatus of claim 7, wherein:
the seal body includes a first internal face opposite a second
internal face, the internal faces being disposed about the bore;
and
the rigid annulus is slidably mounted between the first internal
face and the second internal face.
9. The apparatus of claim 7, additionally comprising a low-friction
coating applied to the instrument seal.
10. The apparatus of claim 7, wherein the laterally-compliant
annulus is corrugated and is disposed between the rigid annulus and
a part of the seal body axially displaced from the rigid
annulus.
11. The apparatus of claim 10, wherein:
the seal body includes a first internal face opposite a second
internal face, the internal faces being disposed about the bore;
and
the rigid annulus is slidably mounted between the first internal
face and the second internal face.
12. The apparatus of claim 11, wherein:
the seal body includes a part that extends axially in the insertion
direction from the second internal face;
the second plane face of the rigid annulus includes a part that
extends radially inwards relative to the first plane face; and
the laterally-compliant annulus is disposed between the
inwardly-extended part of the second plane face of the rigid
annulus and the axially-extended part of the seal body.
13. The apparatus claim 7, wherein the laterally-compliant annulus
is corrugated and is disposed between the rigid annulus and the
seal body.
14. The apparatus of claim 13, wherein:
the laterally-compliant annulus and the instrument seal are
provided by an outer radial zone and an inner radial zone,
respectively, of a single seal molding; and
the seal molding additionally includes:
a rigid annulus anchor radial zone extending between the inner
radial zone and the outer radial zone, the rigid annulus being
attached to the rigid annulus anchor radial zone, and
an anchoring radial zone extending outwards from the outer radial
zone, the anchoring radial zone being attached to the seal
body.
15. The apparatus of claim 14, wherein:
the rigid annulus anchor radial zone extends axially on opposite
sides of the seal molding;
the rigid annulus includes a first rigid annulus half and a second
rigid annular half, each rigid annulus half having a plane face
wherein an annular groove is formed; and
a rigid annulus half is mounted on each side of the seal molding
with the rigid annulus anchor radial zone engaging in the annular
groove of the rigid annulus half.
16. The apparatus of claim 15, additionally comprising a pin
extending from the first rigid annulus half, through the rigid
annulus anchor radial zone and into the second rigid annulus
half.
17. The apparatus of claim 13, wherein:
the seal body includes a first internal face opposite a second
internal face, the internal faces being disposed about the bore;
and
the rigid annulus is slidably mounted between the first internal
face and the second internal face.
18. The apparatus of claim 13, wherein the instrument seal has a
thickness that changes between the rigid annulus and the instrument
port.
19. The apparatus of claim 13, wherein the instrument seal is
substantially conical.
20. The apparatus of claim 13, wherein the instrument seal
comprises:
a layer of a first elastic material having rebound and penetration
resistance; and
a layer of a second elastic material overlaying the layer of the
first elastic material, the second elastic material having inferior
rebound and superior penetration resistance compared with the first
elastic material.
21. The apparatus of claim 13, wherein the laterally-compliant
annulus has a cross section in a plane through the axis comprising
plural linear elements disposed substantially parallel to the axis,
and plural substantially semicircular elements interconnecting
adjacent pairs of the linear elements.
22. The apparatus of claim 13, wherein:
the rigid annulus includes a first rigid annulus half and a second
rigid annulus half, each rigid annulus half having a plane face
wherein an annular groove engaging with the instrument seal is
formed; and
the annulus halves comprise identical moldings each having pins and
pin holes symmetrically arranged such that the pins of one molding
engage in the pin holes of the other molding.
23. The apparatus of claim 1, additionally comprising a low
friction coating applied to the instrument seal.
24. The apparatus of claim 1, wherein the instrument seal has a
thickness that changes between the rigid annulus and the instrument
port.
25. The apparatus of claim 1, wherein the instrument seal is
substantially conical.
26. The apparatus of claim 1, wherein the elastic material
comprises:
a layer of a first elastic material having rebound and penetration
resistance; and
a layer of a second elastic material overlaying the layer of the
first elastic material, the second elastic material having inferior
rebound and superior penetration resistance compared with the first
elastic material.
27. The apparatus of claim 1, additionally comprising a lateral
force transmitting means for transmitting a lateral force from the
instrument directly to the rigid annulus of the instrument seal
assembly to move the instrument seal assembly laterally with a
reduced lateral force between the instrument and the instrument
port.
28. Apparatus for use in a surgical instrument to provide a
gas-tight seal with an instrument passed therethrough, the
instrument having a diameter in a wide range of diameters, the
apparatus comprising:
a seal body including a bore wherethrough the instrument is passed,
the bore defining an axis;
a rigid mounting having a bore;
an instrument seal comprising an elastic material, the instrument
seal extending radially inwards and extending axially from the bore
of the rigid mounting to form an instrument port wherethrough the
instrument is passed in an insertion direction, the instrument port
being substantially perpendicular to the axis, the instrument seal
extending axially in the insertion direction; and
a compliant mounting means for mounting the rigid mounting in the
seal body, the mounting means permitting the rigid mounting to move
freely laterally and restricting axial movement of the rigid
mounting relative to the seal body in response to movement of the
instrument.
29. The apparatus of claim 28, wherein:
the compliant mounting means includes a first internal face formed
in the seal body opposite a second internal face, the internal
faces being disposed about the bore; and
the rigid mounting is slidably mounted between the first internal
face and the second internal face.
30. The apparatus of claim 29, wherein:
the rigid mounting includes a first plane face opposite a second
plane face; and
the compliant mounting means additionally includes:
a first annular wiper attached to the first plane face of the rigid
mounting and contacting the first internal face formed in the seal
body; and
a second annular wiper attached to the second plane face of the
rigid mounting and contacting the second internal face formed in
the seal body.
31. The apparatus of claim 28, wherein the compliant mounting means
includes a compliant annulus disposed between the rigid mounting
and the seal body.
32. The apparatus of claim 31, wherein the compliant annulus is
corrugated and is disposed between the rigid mounting and a part of
the seal body axially displaced from the rigid mounting and the
instrument seal.
33. The apparatus of claim 31, wherein the compliant annulus has a
cross section in a plane through the axis comprising plural linear
elements disposed substantially parallel to the axis, and plural
substantially semicircular elements interconnecting adjacent pairs
of the linear elements.
34. The apparatus of claim 31, wherein:
the compliant annulus and the instrument seal are provided by an
outer zone and an inner zone, respectively, of a single seal
molding; and
the seal molding additionally includes:
a rigid mounting anchor zone extending between the inner zone and
the outer zone, the rigid mounting being attached to the rigid
mounting anchor zone, and
an anchoring zone extending outwards from the outer zone, the
anchoring zone being attached to the seal body.
35. The apparatus of claim 34, wherein:
the rigid mounting anchor zone extends axially on opposite sides of
the seal molding;
the rigid mounting includes a first rigid mounting half and a
second rigid mounting half, each rigid mounting half having a face
wherein a groove is formed; and
a rigid mounting half is mounted on each side of the seal molding
with the rigid mounting anchor zone engaging in the groove in the
rigid mounting half.
36. The apparatus of claim 35, wherein the rigid mounting halves
comprise identical moldings each having pins and pin holes
symmetrically arranged such that the pins of one molding engage in
the pin holes of the other molding.
37. The apparatus of claim 28, additionally comprising a lateral
force transmitting means for transmitting a lateral force from the
instrument directly to the rigid mounting to move the instrument
seal laterally with a reduced lateral force between the instrument
and the instrument port.
38. The apparatus of claim 28, additionally comprising a
low-friction coating applied to the instrument seal.
39. The apparatus of claim 28, wherein the instrument seal has a
thickness that changes between the compliant mounting means and the
instrument port.
40. The apparatus of claim 28, wherein the instrument seal is
substantially conical.
41. The apparatus of claim 28, wherein the elastic material
comprises:
a layer of a first elastic material having rebound and penetration
resistance; and
a layer of a second elastic material overlaying the layer of the
first elastic material, the second elastic material having inferior
rebound and superior penetration resistance compared with the first
elastic material.
42. Apparatus for use in a surgical instrument to provide a
gas-tight seal with an instrument passed therethrough, the
instrument having a diameter in a wide range of diameters, the seal
comprising:
a seal body including a bore wherethrough the instrument is passed,
the bore defining an axis; and
an instrument seal assembly, including:
a rigid annulus, and
an instrument seal comprising an elastic material, the instrument
seal extending radially outwards from an instrument port therein
wherethrough the instrument is passed in an insertion direction,
the instrument port being substantially perpendicular to the axis,
the instrument seal being substantially co-planar with the
instrument port the instrument seal assembly being mounted in the
seal body, and forming a gas-tight seal therewith, in a manner that
restricts axial movement of the instrument seal assembly and that
allows free lateral movement of the instrument seal assembly and
that allows the instrument seal assembly to move freely laterally
in response to movement of the instrument.
43. The apparatus of claim 42, wherein the instrument seal has a
thickness that decreases radially towards the instrument port.
44. The apparatus of claim 42, wherein the instrument seal has a
thickness, the thickness being reduced in a localized area
surrounding the instrument port.
45. The apparatus of claim 42, wherein the instrument seal assembly
additionally includes a laterally-compliant annulus disposed
between the rigid annulus and the seal body, the
laterally-compliant annulus having a cross section in a plane
through the axis comprising plural linear elements disposed
substantially parallel to the axis, and plural substantially
semicircular elements interconnecting adjacent pairs of the linear
elements.
46. The apparatus of claim 42, wherein:
the rigid annulus includes a first rigid annulus half and a second
rigid annulus half, each rigid annulus half having a plane face
wherein an annular groove engaging with the instrument seal is
formed; and
the annulus halves comprise identical moldings each having pins and
pin holes symmetrically arranged such that the pins of one molding
engage in the pin holes of the other molding.
Description
FIELD OF THE INVENTION
The invention relates to a gas-tight seal for use in a surgical
instrument to provide a gas-tight seal with an instrument passed
through the seal. The seal can form a gas-tight seal with
instruments having a wide range of diameters.
BACKGROUND OF THE INVENTION
Trocar tubes used in laparoscopic surgery are normally fitted with
a gas-tight seal to maintain pneumoperitoneum when a laparoscopic
instrument is inserted into the trocar tube. The gas-tight seal is
normally built into the rear housing attached to the cannula of the
trocar tube, and forms a gas-fight seal with an instrument having
an outside diameter that is similar to the internal diameter of the
cannula.
In the course of laparoscopic surgery, it is often necessary to
insert into the trocar tube a laparoscopic instrument having a
diameter that is less than the diameter of the cannula. The
gas-tight seal built into the trocar tube cannot provide an
adequate gas-tight seal with such a smaller-diameter instrument
since known gas-tight seals suffer from an inability to accommodate
a wide range of instrument diameters. Known gas-fight seals leak
when a smaller-diameter instrument is inserted, and/or impose
excessive friction when a larger-diameter instrument is inserted.
Known gas-tight seals also have an increased tendency to leak with
a smaller-diameter instrument when the instrument is displaced
laterally.
In known gas-tight seals, a thin, circular piece of an elastic
material is rigidly supported at its periphery. In the center of
the elastic material is a circular instrument port through which
the instrument passes. The elastic material surrounding the
instrument port contacts the instrument, which forms the gas-tight
seal. The inability of known gas-tight seals to seal with
instruments having a large range of diameters results from this
basic construction.
The instrument port must be smaller than the diameter of the
instrument so that the instrument can deform the elastic material
surrounding the instrument port to form the seal with the
instrument. Consequently, when the seal is to accommodate a range
of instrument diameters, the instrument port must be smaller than
the minimum of the range of instrument diameters for which the seal
is designed, so that a minimum-diameter instrument can deform the
elastic material. Deforming the elastic material results in a
radial force between the elastic material and the instrument. This
holds the elastic material in contact with the instrument and
maintains the gas-tight seal.
An instrument port diameter that produces the required amount of
radial force for a minimum-diameter instrument results in a greater
radial force when a larger-diameter instrument is inserted. The
greater radial force increases friction between the seal and the
instrument. With known gas-fight seals, the maximum of the diameter
range, above which friction is so great as to make it impossible to
manipulate the instrument, may not be a great deal larger than the
minimum of the diameter range, below which the gas-tight seal
leaks.
In known gas-tight seals, the radial force between the elastic
material and the instrument at the minimum of the diameter range
must be increased if the instrument is to be allowed to move
laterally in the seal. The increased radial force is required to
keep the elastic material remote from the direction of lateral
displacement in contact with the instrument, and thus to maintain
the gas-tight seal. This increase in the radial force further
increases friction between the seal and the larger-diameter
instrument, and thus further limits the diameter range that the
seal will accommodate.
To enable instruments with a range of diameters to be used in the
same trocar tube, and to form a gas-tight seal with instruments
having a range of diameters, it is known to fit a trocar tube with
an auxiliary gas-tight seal. The auxiliary gas-tight seal
supplements the diameter range capability of the main gas-tight
seal. For example, the applicant's assignee sells trocar assemblies
in which the trocar tube has a 10 mm (0.4") diameter cannula that
can accommodate instruments ranging from 5 mm (0.2") and 10 mm
(0.4") in diameter. The trocar tube accommodates this range of
diameters by providing two auxiliary door-type gas-tight seals in
addition to the main gas-tight seal. The main gas-tight seal, which
will be described further below, seals with instruments between 9
and 10 mm in diameter; a first auxiliary seal seals with
instruments 7 to 8 mm in diameter, and a second auxiliary seal
seals with instruments 5 and 6 mm in diameter.
The two auxiliary door-type gas-tight seals are stored on opposite
sides of the rear housing of the trocar tube. Each auxiliary seal
is mounted in a track that runs up the side and across the rear
face of the housing. Before a smaller-diameter instrument is
inserted into the cannula, the surgeon must slide the appropriate
auxiliary gas-tight seal up the track from the storage position
into place on the proximal face of the housing. In this position,
the auxiliary seal forms a seal with a lip on the main gas-fight
seal, and seals with the smaller-diameter instrument passed through
it. If another instrument with a different diameter is later to be
inserted into the cannula, the one auxiliary seal must be returned
to its storage position, and, if necessary, the other auxiliary
seal deployed.
Time is needed in the operating room to move each auxiliary gas
seal back and forth from its storage position to its operating
position. The process of sliding the auxiliary gas-tight seal can
be tedious, especially for gloved hands. The surgeon must remember,
or double check, which auxiliary seal is in place before inserting
an instrument into the trocar tube. If the auxiliary seal is too
large for the instrument, the seal will leak; if the auxiliary seal
is too small for the instrument, there will be excessive friction
between the seal and the instrument. With an extreme diameter
mismatch, the instrument can tear the seal, which would then
require that the trocar tube be replaced.
As an example of a different approach to accommodating in a single
trocar tube instruments with a range of diameters, U.S. Pat. No.
5,104,383 describes a completely detachable auxiliary seal that
allows an instrument as small as 5 mm in diameter to be used in a
10 mm cannula. The auxiliary seal is installed into the rear of the
housing before a smaller-diameter instrument is inserted into the
cannula. A single auxiliary gas-tight seal is made to accommodate
instruments with a range of diameters by including a rigid
stabilizer plate to prevent the instrument from being moved
laterally relative to the cannula. The stabilizer plate keeps the
instrument centered in the cannula, and prevents gas leaks caused
by the instrument going off center in the auxiliary seal.
Thus, with known auxiliary gas-tight seals, either a single, wider
range, auxiliary gas-tight seal or plural, narrower-range,
auxiliary gas-tight seals can be used to accommodate instruments
with a range of diameters. If plural, narrower-range, auxiliary
gas-tight seals are used, the surgeon has to ensure that the
auxiliary gas-tight seal is the appropriate one for the diameter of
the instrument being used. If a single, wider-range auxiliary
gas-tight seal is used, the surgeon must accept that the range of
lateral movement of the instrument in the cannula is limited if the
auxiliary gas-tight seal is to seal effectively with an instrument
at the minimum of the diameter range.
OBJECTS AND SUMMARY OF THE INVENTION
To overcome the problems of known gas-tight seals, it is an object
of the invention to provide a gas-tight seal that accommodates
instruments with a wide range of diameters, for example, from 4 to
12 mm.
It is a further object of the invention to provide a gas-tight seal
that effectively provides a leak-free seal with an instrument with
a diameter at the minimum of the range of diameters.
It is a further object of the invention to provide a gas-tight seal
that imposes an acceptably low level of friction on an instrument
with a diameter at the maximum of the range of diameters.
It is an object of the invention to provide a gas-tight seal that
does not limit the lateral movement of the instrument.
It is an object of the invention to provide a gas-tight seal that
can be built into a trocar tube to allow the trocar tube to
accommodate instruments with a wide range of diameters, for
example, from 4 to 12 mm.
Finally, it is an object of the invention to provide a gas-tight
seal in which the elastic seal resists penetration by pronged
instruments.
Accordingly, the invention provides a seal for use in a surgical
instrument to provide a gas-tight seal with an instrument passed
through the seal. The seal can form a gas-tight seal with an
instrument having a diameter within a wide range of diameters. The
seal comprises a seal body, an instrument seal, and a
laterally-compliant seal mounting. The seal body includes a bore
through which the instrument is passed. The instrument seal is made
of an elastic material. The instrument seal extends radially
outwards from an instrument port formed in the instrument seal
through which the instrument is passed. The instrument port is
substantially perpendicular to the axis. The instrument seal also
extends axially from the instrument port in the direction opposite
to that in which the instrument is passed through the instrument
port. The laterally-compliant seal mounting mounts the instrument
seal to the seal body, forms a gas-tight seal between the
instrument seal and the seal body, and allows the instrument seal
to move freely laterally in response to lateral movement of the
instrument.
The instrument seal forms the gas-tight seal with the instrument.
The laterally-compliant seal mounting device allows the instrument
to move the instrument seal laterally with a relatively small
lateral force. This enables a significant reduction to be made in
the radial force that the instrument seal is required to exert on
the instrument to maintain the gas-tight seal as the instrument is
moved laterally. This, in turn, increases the range of instrument
diameters that can be used in the seal.
The lateral extension of the instrument seal provides a sloping
surface that is contacted by the instrument being passed though the
instrument port. The distal end of the instrument contacting the
sloping surface of the instrument seal progressively opens the
instrument port and enables the instrument to enter the instrument
port without the distal end of the instrument piercing the
instrument seal.
The laterally-extended instrument seal may be substantially conical
with the instrument seal at the apex of the cone. The thickness of
the instrument seal may be radially varied to ensure that the
instrument enters the instrument port and does not penetrate the
instrument seal elsewhere. The instrument seal may be made of
superimposed layers of two materials, one having a superior elastic
characteristic and the other having a superior penetration
resistance characteristic.
In one embodiment, the laterally-compliant seal mounting device
includes a rigid annulus, and a laterally-compliant annulus
disposed between the rigid annulus and the seal body. The
instrument seal is attached to the rigid annulus with the
instrument port inside the annulus.
The laterally-compliant annulus and the instrument seal are
preferably provided by an outer radial zone and an inner radial
zone, respectively, of a single seal molding. The seal molding
additionally includes a rigid annulus anchor radial zone and an
anchoring radial zone. The rigid annulus anchor radial zone extends
between the inner radial zone and the outer radial zone. The rigid
annulus is attached to the rigid annulus anchoring radial zone. The
anchoring radial zone extends outwards from the outer radial zone
and is attached to the seal body.
The compliance of the laterally-compliant annulus is maximized by
providing it with a cross section in a plane through the axis that
comprises plural linear elements disposed substantially parallel to
the axis, and plural substantially semicircular elements
interconnecting adjacent pairs of the linear elements.
A low-friction coating may be applied to the instrument seal to
reduce friction between the instrument seal and the instrument.
This further increases the range of instrument diameters that can
be used with the seal.
The seal may also include a lateral force transmitting device that
transmits a lateral force from the instrument directly to the
laterally-compliant seal mounting device. The directly-transmitted
lateral force moves the instrument seal laterally as the instrument
is moved laterally. The lateral force transmitting device
preferably transmits the lateral force from the instrument directly
to the rigid annulus, and thence to the instrument seal.
The lateral force transmitting device reduces the lateral force
between the instrument and the instrument seal required to move the
instrument seal laterally. This enables a further reduction to be
made in the radial force that the instrument seal must apply to the
instrument to maintain a gas-tight seal as the instrument is moved
laterally. Reducing the radial force between the instrument seal
and the instrument increases the range of instrument diameters that
can be used with the seal.
The invention also provides a seal for use in a surgical instrument
to provide a gas-tight seal with an instrument passed through the
seal. The seal will form a gas-tight seal with an instrument having
a diameter within a wide range of diameters. The seal comprises a
seal body, a rigid mounting, an instrument seal, and a compliant
mounting. The seal body includes a bore through the instrument is
passed. The rigid mounting also includes a bore. The instrument
seal is made of an elastic material and extends radially inwards
and extends axially from the bore of the rigid mounting to form an
instrument port through which the instrument is passed. The
instrument port is substantially perpendicular to the axis. The
instrument seal extends axially in the direction in which the
instrument is inserted into the instrument port. The compliant
mounting is disposed between the rigid mounting and the seal
body.
The instrument seal forms the gas-tight seal with the instrument
and is mounted in the rigid mounting. The rigid mounting is, in
turn, mounted to the seal body by the compliant mounting. The rigid
mounting effectively isolates the instrument seal from the
compliant mounting. The compliant mounting allows the instrument to
move the instrument seal laterally with a relatively small lateral
force. This enables a significant reduction to be made in the
radial force that the instrument seal is required to exert on the
instrument to maintain the gas-tight seal as the instrument is
moved laterally. This, in turn, increases the range of instrument
diameters that can be used in the seal.
The seal may also include a low-friction coating applied to the
instrument seal, as described above. The seal may also include a
lateral force transmitting device that transmits a lateral force
from the instrument directly to the rigid mounting, and thence to
the instrument seal, substantially as described above.
Finally, the preferred embodiment of the invention provides a seal
for use in a surgical instrument to provide a gas-tight seal with
an instrument passed through the seal. The seal can form a
gas-tight seal with an instrument having a diameter within a wide
range of diameters. The seal comprises a seal body, an instrument
seal, and a laterally-compliant seal mounting. The seal body
includes a bore through which the instrument is passed. The seal
molding is made of an elastic material, and extends radially
outwards from an instrument port in the seal molding through which
the instrument is passed. The instrument port is substantially
perpendicular to the axis. The instrument seal is substantially
co-planar with the instrument port. The laterally-compliant seal
mounting mounts the instrument seal to the seal body, forms a
gas-tight seal between the instrument seal and the seal body, and
allows the instrument seal to move freely laterally in response to
lateral movement of the instrument.
Penetration of the instrument port in this substantially flat
instrument seal is aided by radially reducing the thickness of the
instrument seal towards the instrument port. Alternatively, the
thickness of the instrument seal can be reduced in a localized area
surrounding the instrument port.
The seal may also include a low-friction coating applied to the
seal molding, as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an auxiliary gas-tight seal
according to the invention aligned with the rear housing of a
trocar tube, prior to attaching the auxiliary gas-tight seal to the
rear housing.
FIG. 2 is a cross sectional view of the auxiliary gas-tight seal
according to the invention attached to the rear housing of a trocar
tube.
FIG. 3A is an exploded perspective view of an auxiliary gas-tight
seal according to the invention showing its three main
components.
FIG. 3B is an exploded cross-sectional view of auxiliary gas-tight
seal according to the invention.
FIG. 3C is a perspective view of the laterally-compliant seal of
the auxiliary gas-tight seal according to the invention showing how
laterally displacing an instrument inserted into the instrument
port laterally displaces the instrument seal and the stabilizing
ring.
FIG. 3D is a cross-sectional view of part of an alternative
embodiment of the cap and the base of an auxiliary gas-tight seal
according to the invention.
FIG. 4A is a cross-sectional view of the lower part of the base of
the auxiliary gas-tight seal according to the invention and the
rear housing of a trocar tube prior to engaging the lugs on the
base with grooves in the rear housing.
FIG. 4B is a cross-sectional view of the lower part of the base of
the auxiliary gas-tight seal according to the invention and the
rear housing of a trocar tube prior to engaging the lugs on the
base with grooves in the rear housing.
FIG. 4C is a cross-sectional view of the one of the lugs on the
base of the auxiliary gas-tight seal according to the invention
engaged with one of the grooves in the rear housing of the trocar
tube. The drawing shows how the lug is tapered.
FIG. 5A is a cross-sectional view of the preferred embodiment of an
auxiliary gas-tight seal with a conical instrument seal according
to the invention.
FIG. 5B is an exploded cross-sectional view of the preferred
embodiment of an auxiliary gas-tight seal with a conical instrument
seal according to the invention.
FIG. 5C is a plan view of one of the stabilizing ring halves used
in the preferred embodiment of an auxiliary gas-tight seal
according to the invention.
FIG. 5D is a cross-sectional view of one of the stabilizing ring
halves used in the preferred embodiment of an auxiliary gas-fight
seal according to the invention.
FIG. 6A is a cross-sectional view of the seal molding of an
auxiliary gas-tight seal with a bimaterial conical instrument seal
according to the invention.
FIG. 6B is a cross-sectional view of the seal molding of an
auxiliary gas-tight seal with a first type of tapered conical
instrument seal according to the invention.
FIG. 6C is a cross-sectional view of the seal molding of an
auxiliary gas-tight seal with a second type of tapered conical
instrument seal according to the invention.
FIG. 6D is a cross-sectional view of the seal molding of an
auxiliary gas-tight seal with a tapered flat instrument seal
according to the invention.
FIG. 6E is a cross-sectional view of the seal molding of an
auxiliary gas-tight seal with a flat instrument seal with a
recessed area around the instrument port according to the
invention.
FIG. 7 is a cross-sectional view of an auxiliary gas-tight seal
with a conical instrument seal and a proximally-extending compliant
mounting according to the invention.
FIG. 8 is a cross-sectional view of a first alternative embodiment
of an auxiliary gas-tight seal according to the invention.
FIG. 9 is a cross-sectional view of a second alternative embodiment
of an auxiliary gas-tight seal according to the invention.
FIG. 10 is a cross-sectional view of a third alternative embodiment
of an auxiliary gas-tight seal according to the invention.
FIG. 11A is a plan view of the stabilizing ring and instrument seal
of an auxiliary gas-tight seal according to the invention including
a first embodiment of a lateral force transmitting mechanism
according to the invention.
FIG. 11B is a cross-sectional view of the stabilizing ring and
instrument seal of the auxiliary gas-tight seal according to the
invention including the first embodiment of the lateral force
transmitting mechanism according to the invention.
FIG. 11C is a plan view of the stabilizing ting and instrument seal
of the auxiliary gas-tight seal according to the invention
including the first embodiment of the lateral force transmitting
mechanism according to the invention with a larger-diameter
instrument inserted.
FIG. 12A is a plan view of the stabilizing ring and instrument seal
of an auxiliary gas-tight seal according to the invention including
a second embodiment of the lateral force transmitting mechanism
according to the invention.
FIG. 12B is a cross-sectional view of the stabilizing ring and
instrument seal of the auxiliary gas-tight seal according to the
invention including the second embodiment of the lateral force
transmitting mechanism according to the invention.
FIG. 13 is a plan view of the stabilizing ring and instrument seal
of an auxiliary gas-tight seal according to the invention including
a third embodiment of the lateral force transmitting mechanism
according to the invention.
FIG. 14A is a plan view of the stabilizing ring and instrument seal
of an auxiliary gas-tight seal according to the invention including
a fourth embodiment of the lateral force transmitting mechanism
according to the invention.
FIG. 14B is a plan view of the stabilizing ring and instrument seal
of the auxiliary gas-tight seal according to the invention
including the fourth embodiment of the lateral force transmitting
mechanism according to the invention with a larger-diameter
instrument inserted into the instrument port.
FIG. 15A is a plan view of an auxiliary gas-tight seal according to
the invention including a fifth embodiment of a lateral force
transmitting mechanism according to the invention.
FIG. 15B is a cross-sectional view of the auxiliary gas-tight seal
according to the invention including the fifth embodiment of the
lateral force transmitting mechanism according to the
invention.
DETAILED DESCRIPTION OF THE INVENTION
The conventional gas-tight trocar tube seal, described above, uses
the same piece of elastic material to form the gas-tight seal with
the instrument, and to accommodate lateral displacement of the
instrument. The need to accommodate lateral displacement of the
instrument requires that, to prevent the seal from leaking, the
radial force between the elastic material and the instrument be
increased for an instrument at the minimum of the range of
diameters. This reduces the maximum of the range of diameters above
which there is excessive friction between the elastic material and
the instrument.
The gas-tight seal according to the invention uses different
structures to provide the gas-tight seal with the instrument and to
accommodate lateral displacement of the instrument. This enables
the radial force between the gas-tight seal and the instrument to
be reduced for an instrument at the minimum of the range of
diameters. This, in turn, reduces friction between the seal and a
larger-diameter instrument, and thus increases the maximum of the
range of diameters.
Additionally, in the gas-tight seal according to the invention, at
least the part of the seal that contacts the instrument is
preferably dry-lubricated. This provides a further reduction in
friction between the seal and the instrument, and further increases
the maximum of the range of diameters. Accordingly, the gas-tight
seal according to the invention presently provides a gas-tight seal
with instruments having a greater than 3:1 range of diameters, and
maintains the gas-tight seal when an instrument in the diameter
range is laterally displaced. The present preferred embodiment
provides a gas-tight seal with instruments ranging in diameter from
4 mm to 12 mm (0.16" to 0.48").
The preferred embodiment of the gas-tight seal according to the
invention will next be described. The preferred embodiment is an
auxiliary gas-tight seal that is intended to be attached to the
rear housing of a trocar tube after the trocar assembly has been
used to puncture the body wall, and the trocar has been withdrawn
from the trocar tube.
The preferred embodiment is an auxiliary gas-tight seal because the
self-shielding mechanism of the trocar of the trocar assembly sold
by the applicant's assignee operates by snapping the trocar
distally into the cannula after the trocar tip has penetrated the
body wall. In this trocar assembly, the trocar passes through a
large-diameter, conventional gas-tight seal. If the gas-tight seal
according to the invention were substituted for the conventional
large-diameter gas-tight seal, friction between the gas-tight seal
according to the invention and the trocar would be sufficiently
high to impede the operation of the self-shielding mechanism.
Friction in the gas-tight seal according to the invention is higher
than in the large-diameter conventional gas-tight seal because the
considerably smaller diameter instrument port in the gas-tight seal
according to the invention. Nevertheless, friction in the gas-tight
seal according to the invention is significantly reduced compared
with a conventional gas-tight seal having the same diameter
instrument port.
The gas-tight seal according to the invention is not limited to use
as an auxiliary gas-tight seal, however. A seal according to the
invention could be built into, and form the main gas-tight seal in,
a trocar tube for use in a trocar assembly in which the
self-shielding mechanism does not move the trocar rapidly through
the seal. Such a trocar is shown, for example, in U.S. Pat. No.
4,601,710.
FIG. 1 shows a perspective view of the auxiliary gas-tight seal 10
according to the invention aligned with the rear housing 12 of the
trocar tube 14, just prior to attaching the auxiliary gas-tight
seal to the rear housing. The rear face 16 of the rear housing 12
includes the main gas-tight seal 18 in its center. On opposite
sides of rear face are the side walls 20 in which are formed the
grooves 22. The rear housing includes the side walls 20 and the
grooves 22 as part of the mounting for the two door-type auxiliary
gas-tight seals (not shown) formerly fitted to the rear housing, as
described above. The auxiliary gas-tight seal 10 includes lugs that
engage in the grooves 22 to retain the auxiliary trocar seal in
position on the rear face 16 of the rear housing 12. This way of
attaching the auxiliary gas-tight seal 10 allows the auxiliary
gas-tight seal 10 to replace the conventional door-type auxiliary
gas-tight seals formerly fitted without the need to change the
tooling used to mold the rear housing 12.
A cross section of the auxiliary gas-tight seal 10 attached to the
rear housing 12 is shown in FIG. 2. The auxiliary gas-tight seal 10
is shown in perspective and in cross section in FIGS. 3A and 3B,
respectively. The auxiliary gas-tight seal 10 will now be described
in detail with reference to these figures.
The auxiliary gas-tight seal 10 includes three main components: the
seal body 30 which attaches to the rear housing 12, the instrument
seal 32, and the seal mounting 34 for the instrument seal 32. The
instrument seal is a piece of a elastic material in which the
instrument port 38 is formed, preferably in its center. The
instrument seal 32 forms the gas-tight seal with an instrument
passed through the instrument port 38. The instrument seal 32 is
mounted in the seal mounting 34 to form the laterally-compliant
seal 40.
The seal mounting 34 is laterally compliant to allow the instrument
seal 32 to move laterally in response to lateral movement of the
instrument passed through the instrument port 38. The seal mounting
34 is preferably also axially stiff, to hold the instrument seal 32
in position axially when an instrument is inserted into or
withdrawn from the instrument port. The seal mounting 34 includes
the anchoring ting 42 and the stabilizing ting 44. The stabilizing
ring includes the stabilizing ring halves 44A and 44B, and the
locking pins 46.
The preferred embodiment includes the seal molding 48, a part of
which provides the instrument seal 32, and the rest of which
provides pan of the seal mounting 34. The seal molding 48 includes
four distinct, radially separated zones, the instrument seal 32,
the stabilizing ting anchor 50, the corrugated zone 52, and the
anchoring ring 42. The seal molding 48 is made of an elastic
material, preferably silicone rubber, but it can alternatively be
molded from other suitable elastic materials, such as latex.
The instrument seal 32 and the seal mounting 34 could alternatively
be separate components joined at the stabilizing ring 44. This
alternative construction is more complex, but enables different
materials to be used for the instrument seal 32 and the seal
mounting 34. For example, the seal mounting 34 could be made from
an inelastic material, such as Mylar.TM. film.
The part of the seal molding 48 providing the instrument seal 32
forms a gas-tight seal with an instrument (not shown) passed
through the instrument port 38 in the center of the seal molding.
Compared with the part of the seal molding 48 forming the
corrugated zone 52, the part forming the instrument seal 32 is
relatively thick, about 1 mm (0.04") in the preferred embodiment.
This enables this part of the seal molding to exert sufficient
radial force against the instrument to form a gas-tight seal, even
with an instrument at the minimum of the range of diameters. The
part of the seal molding forming the instrument seal 32 is also
relatively thick to prevent it from being tom when a hook-shaped
instrument is withdrawn from the instrument port.
The present embodiment accommodates instruments having a range of
diameters, i.e., the instrument seal 32 forms a gas-tight seal with
an instrument of a minimum diameter, and provides an acceptably low
level of friction with an instrument as large as the maximum
diameter. The minimum instrument diameter that can be accommodated
depends on the diameter of the instrument port 38. In the present
preferred embodiment, the instrument port 38 is 3 mm (0.12") in
diameter. With an instrument port of this diameter, the instrument
seal 32 forms a gas-tight seal with an instrument as small as 4 mm
(0.16") in diameter. The preferred embodiment can be adapted to
accommodate different ranges of instrument diameters by changing
the diameter of the instrument port 38. For example, a 2.2 mm
(0.09") diameter instrument port will provide a gas-tight seal with
a 3 mm (0.12") diameter instrument.
When a larger-diameter instrument is inserted through the
instrument port 38, the instrument stretches the elastomeric
material of the seal molding 48 forming the instrument seal 32.
This causes the part of the seal molding providing the instrument
seal 32 to exert a radial force against the instrument, which
results in friction between the instrument seal 32 and the
instrument. To reduce this friction, the seal molding 48 is
preferably coated with a dry lubricant. Reducing friction increases
the maximum of the range of instrument diameters that the auxiliary
gas-tight seal 10 can accommodate without excessive friction
between the instrument and the instrument seal.
The preferred dry lubricant is poly-p-xylxylene, a crystalline
organic solid, a thin film of which is low vacuum deposited from
the vapor phase onto the seal molding 48. Poly-p-xylxylene is sold
under the brand name Parylene C by Union Carbide. An alternative
dry lubricant is titanium, vapor deposited onto the surface of the
seal molding 48. Other dry lubricants, sold by Spire Corporation,
Bedford, Mass., include: SPI-ARGENT.TM. and SPI-ARGENT II.TM.,
which are ion beam deposited silver-based coatings; SPI-Met.TM.,
and SPI-Silicone.TM..
It is only necessary to deposit the dry lubricant coating on the
part of the seal molding 48 forming the instrument seal 32, but it
is simpler to deposit the coating on all the seal molding. Other
suitable surface modification techniques or anti-friction coatings
can also be used. With the dry lubricant coating, an instrument
having a diameter as large as three times the minimum diameter can
be inserted into the instrument port 38 in the seal molding 48
without excessive friction. Thus, in the present preferred
embodiment, an instrument as large as 12 mm (0.48") in diameter can
be inserted into the 3 mm diameter instrument port without
excessive friction. It is envisaged that the present embodiment can
be developed to accommodate a range of instrument diameters greater
than the present 3:1.
The seal mounting 34 for the instrument seal 32 comprises the
stabilizing ting 44; and the stabilizing ring anchor 50, the
corrugated zone 52, and the anchoring ting 42, all of which form
part of the seal molding 48. The part of the seal molding 48
forming the anchoring ring 42 is considerably thicker than the part
of the seal molding forming the instrument seal 32. The anchoring
ting 42 is relatively rigid, and serves to locate the
laterally-compliant seal 40 in the seal body 30. The anchoring ring
is located in an annular groove formed by the inner annular step 58
in the base 60 and the annular step 64 in the cap 66. The face 54
and the face 56 of the anchoring ring contact the inner annular
step 58 in the base 60, and the face 62 of the anchoring ring
contacts the annular step 64 in the cap 66. When the cap and the
base are mated to form the seal body 30, the anchoring ring is
slightly compressed between the annular step 64 and the inner
annular step 58. This forms a gas-tight seal between the anchoring
ring and the seal body.
The part of the seal molding 48 forming the stabilizing ting anchor
50 is located between the instrument seal 32 and the corrugated
zone 52. The stabilizing ring anchor 50 is an annular region in
which the thickness of the seal molding 48 is increased on both
sides. The stabilizing ring anchor serves to locate the seal
molding 48 laterally with respect to the stabilizing ring 44.
The corrugated zone 52 interconnects the stabilizing ring anchor 50
and the anchoring ring 42. The part of the seal molding 48 forming
the corrugated zone 52 is between one tenth and one half of the
thickness of the part of the seal molding forming the instrument
seal 32. In the preferred embodiment, the part of the seal molding
forming the corrugated zone is about 0.2 mm (0.008") thick, and is
also corrugated, as shown. The thinness of the corrugated zone 52
and its corrugated structure provide lateral compliance between the
inner periphery (i.e., the stabilizing ring 44) and the outer
periphery (i.e., the anchoring ring 42) of the corrugated zone. The
amount of radial force that must be applied to the stabilizing ring
to displace laterally the stabilizing ring and the part of the
corrugated zone to which it is attached is relatively small. Thus,
the lateral force that an instrument passed through the instrument
port 38 must apply to the instrument seal 32 to displace laterally
the instrument seal 32, the stabilizing ting 44, and the part of
the corrugated zone to which the stabilizing ring is attached is
relatively small. Consequently, the additional radial force that
the instrument seal 32 must apply to an instrument having a
diameter at the minimum of the range of diameters to maintain the
gas-tight seal with the instrument as the instrument is displaced
laterally is also relatively small. Reducing the additional radial
force reduces the radial force that the instrument seal 32 exerts
when a larger-diameter instrument is inserted into the instrument
port 38. This, in turn, reduces friction between the seal and the
instrument and increases the range of instrument diameters that the
seal can accommodate.
The stabilizing ting 44 interconnects the instrument seal 32 and
the corrugated zone 52, and transmits any radial force applied to
the instrument seal 32 uniformly to the corrugated zone 52. The
stabilizing ring 44 also preferably transmits axial forces
resulting from inserting and withdrawing an instrument into and
from the instrument port 38 directly to the seal body 30, i.e., to
the base 60 when an instrument is inserted, and to the cap 66 when
an instrument is withdrawn. The stabilizing ring, by isolating
axial forces from the corrugated zone 52, and by transmitting
radial forces uniformly to the corrugated zone, enables the
strength of the corrugated zone to be minimized, and the lateral
compliance of the corrugated zone to be maximized.
The stabilizing ring 44 comprises the stabilizing ring halves 44A
and 44B, and the pins 46. The stabilizing ring halves are
annulus-shaped moldings of a suitable low-friction plastic, such as
ABS, polycarbonate, or PTFE. Each stabilizing ring half includes in
one face the annular groove 68 that mates with the stabilizing ring
anchor 50 in the seal molding 48. The stabilizing ring halves 44A
and 44B are held in place on opposite sides of the seal molding 48
by the plural pins 46 inserted through one of the stabilizing ring
halves (e.g., the stabilizing ring half 44A), the stabilizing ring
anchor 50, and the other of the stabilizing ring halves (e.g., the
stabilizing ring half 44B). The pins 46 pass through the
stabilizing ring anchor 50, where the material of the seal molding
48 is thicker, and forms a gas-tight seal with each pin 30. This
prevents the pins 46 from providing a gas leakage path.
The behavior of the laterally-compliant seal 40 when an instrument
passed through the instrument port is laterally displaced will now
be contrasted with the behavior of the conventional gas-tight seal.
In the conventional gas-tight seal, the elastic material
surrounding the instrument port is rigidly mounted at its
periphery. The elastic material surrounding the instrument port
stretches to accommodate lateral displacement of the instrument.
Sufficient excess radial force must be provided between the elastic
material and the instrument to keep the elastic material remote
from the direction of the lateral displacement in contact with the
instrument and therefore preserve the gas-tight seal.
In the laterally-compliant seal 40 in the auxiliary gas-tight seal
10 according to the invention, the elastic material surrounding the
instrument port 38 is also rigidly mounted at its periphery, but
the rigidly-mounted elastic material is, in turn, compliantly
mounted. When the instrument passing through the instrument port is
displaced laterally, the seal mounting 34 allows the whole of the
instrument seal 32 to move laterally. This is illustrated in FIG.
3C, in which the center line 41 of the instrument (not shown) is
displaced laterally to the point indicated by the line 43. The
lateral movement of the instrument seal is accommodated by the
corrugated zone 52, the thin, corrugated material of which makes it
laterally compliant. The force between the instrument and the
instrument port, and hence the amount of stretching of the elastic
material surrounding the instrument port, required to displace the
instrument seal laterally is small. Thus, compared with a
conventional seal, the laterally-compliant seal 40 requires that
considerably less excess radial force be provided between the
instrument seal and the instrument to maintain contact with
instrument when the instrument is laterally displaced. This, in
turn, reduces the amount of friction between the instrument seal
and the instrument when a larger-diameter instrument is inserted
into the instrument port, and allows the seal to accommodate a
larger range of instrument diameters.
The seal body 30 includes the base 60 and the cap 66, as shown in
FIG. 3A. The base 60 is a molding of a suitable plastic, such as
ABS, or polycarbonate. The base includes the internal face 70 over
which the stabilizing ring 44 of the seal mounting 34 can slide
laterally. The base also includes the inner annular step 58 and the
outer annular step 80. The inner annular step 58, together with the
annular step 64 in the cap, locates the anchoring ring 42 of the
seal molding 48, as described above. The outer annular step 80
abuts the edge 81 of the cap 60, which defines the axial location
of the cap 66 relative to the base 60. This, in turn, defines the
amount of compression applied to the anchoring ring 42 when the cap
and the base are mated to form the seal body 30. This also defines
the clearance between the internal face 70 of the base 60 and the
internal face 78 of the cap 66, and hence the clearance between the
stabilizing ring 44 and the internal faces 70 and 78.
The base also includes the bore 72, which has a diameter of
slightly greater than the diameter as the largest-diameter
instrument that can be accommodated by the main gas-tight seal in
the trocar tube, plus twice the thickness of the instrument seal
32. Surrounding the bore 72 are the lugs 74 and the plane sealing
surface 76 with which the auxiliary gas-tight seal 10 is attached
to the rear face 16 of the rear housing 12 (FIG. 1). The lugs 74
are preferably tapered.
The lugs 74 and the plane sealing surface 76 are specific to the
preferred way of attaching the auxiliary gas-tight seal 10 to the
rear housing of the trocar tube sold by the applicant's assignee.
The auxiliary gas-tight seal 10 could be attached to the rear
housing of the trocar tube made by the applicant's assignee in
other ways, which would require a different arrangement of the base
60 and/or the cap 66. Moreover, the auxiliary gas-tight seal 10
could be adapted for attaching to the rear housings of trocar tubes
made by others, which might also require a different arrangement of
the base 60 and/or the cap 66. Finally, a gas-tight seal similar to
the auxiliary gas-tight seal 10 can be built into the rear housing
of a trocar tube, in which case, the base 60 would be formed as pan
of the rear housing molding.
The cap 66 is also a molding of a suitable plastic such as ABS or
polycarbonate. The cap fits over the base 60, and includes the
internal face 78, with respect to which the stabilizing ring 44 of
the seal mounting 34 can slide laterally. The cap 66 also includes
the inner annular step 64 and the edge 81. The annular step 64
clamps the anchoring ring 42 of the seal molding 48 into the
annular step 58 in the base 60, as described above. The edge 81
defines the relative axial location of the base and the cap, as
described above.
The cap 66 also includes the central bore 82, which also has a
diameter of slightly greater than the diameter as the
largest-diameter instrument that can be accommodated by the main
gas-tight seal in the trocar tube, plus twice the thickness of the
instrument seal 32.
The cap 66 is attached to the base 60 by a suitable snap
arrangement, a suitable adhesive, by ultrasonic welding, or by some
other suitable method. The cap may be adapted for attaching the
auxiliary gas-tight seal 10 to the rear housing of the trocar tube
in addition to, or as an alternative to, the attachment
arrangements on the base 60 already described.
As an alternative to the arrangement shown, the cap 66A may be
formed with two annular steps, and the base 60A may be formed with
a single annular step, as shown in FIG. 3D. The cap 66A is formed
with an inner annular step 64A and an outer annular step 80A, and
the base is formed with the wide annular step 58A. The annular
groove formed between the inner annular step 64A in the cap 66A and
the inner part of the wide annular step 58A in the base locates and
seals with the anchoring ring 42. The outer part of the wide
annular step 58A in the base 60A abutting the outer annular step
80A in the cap 66A defines the relative axial location of the base
and the cap.
The arrangement for attaching the auxiliary gas-tight seal 10 to
the rear housing 12 of the trocar tube made by the applicant's
assignee will now be described with reference to FIG. 2. FIG. 2
shows a cross sectional view of the auxiliary gas-tight seal 10 in
place on the rear face 16 of the housing 12 of the trocar tube
14.
In the rear housing 12, the main gas-tight seal 18 is an
elastomeric molding that engages with the rear face 16 as shown.
The main gas-tight seal includes the main sealing lip 84, which
seals with the trocar (not shown) or other instrument passed
through the main gas-tight seal. The main gas-tight seal also
includes the annular inner sealing lip 86, which forms a gas-tight
seal with the spring-loaded door 88. The spring-loaded door 88
swings in the direction indicated by the arrow 90 to form a seal
with the inner sealing lip 86 when no instrument is inserted into
the main gas-tight seal 18.
The main gas-tight seal 18 also includes the annular outer sealing
lip 92, which is provided to form a gas-tight seal with the
door-type auxiliary gas-tight seal formerly included in the rear
housing, as described above. When the auxiliary gas-tight seal 10
is attached to the trocar tube 11 sold by the applicant's assignee,
the outer sealing lip 92 forms a gas-tight seal with the plane
sealing surface 76 of the base 60 of the auxiliary gas-tight seal
10, as shown. The plane sealing surface 76 is kept in contact with
the outer sealing lip 92 by the lugs 74 engaging in the grooves 22
in the rear housing 12.
FIGS. 4A and 4B show a cross section of the rear housing 12 and
part of the base adjacent to the lugs 74 before and after engaging
the lugs in the grooves 22. Each lug includes a cut-away part 94,
which enables the lugs to fit between the walls 20. To attach the
auxiliary gas-tight seal 10 to the rear housing 12, the surgeon
grasps the rear housing in one hand, holds the auxiliary gas-tight
seal in the other, and presents the auxiliary gas-tight seal to the
rear housing such that the cut-away part 94 of each lug is inserted
between the walls 20, as shown in FIG. 4A. The surgeon then rotates
the auxiliary gas-tight seal in a clockwise direction, looking from
the top, to engage the lugs 74 into the grooves 22. The lugs 74 are
tapered, as shown in FIG. 4C, such that, as the auxiliary gas-tight
seal is rotated, the tapered lugs engaging with the grooves 22
moves the plane sealing face 76 into engagement with the outer
sealing lip 92 (see FIG. 2). The surgeon stops rotating the
auxiliary gas-tight seal when the stop 96 on each lug is fully
engaged with the corresponding stop 98 in the grooves 22.
Juxtaposing the stop 96 with the stop 98 and the lugs 74 with the
grooves 22 positively locates the auxiliary gas-tight seal 10 in
all three dimensions relative to the rear housing 12.
The surgeon can then insert an instrument having any diameter in
the specified range of diameters accommodated by the gas-tight seal
into the bore 82, and then through the instrument port 38. The
surgeon can move a smaller-diameter instrument laterally to the
extent defined by the bore 82, if desired.
The surgeon can remove the auxiliary gas-tight seal 10 at any time
simply by removing the instrument from the auxiliary gas-tight
seal, rotating the auxiliary gas-tight seal 10 counter-clockwise
until the lugs 74 disengage from the grooves 22, and withdrawing
the auxiliary gas-tight seal from the rear housing 12.
The shape of the auxiliary gas-tight seal 10 and the simple
attachment mechanism makes it easy to attach the auxiliary
gas-tight seal to, and to remove the auxiliary gas-tight seal from,
the rear housing 12 of the trocar tube 14, even with gloved hands.
However, it is envisaged that, in practice, because the preferred
embodiment of the auxiliary gas-tight seal can accommodate
instruments having a 3:1 range of diameters, for example, from 4 mm
to 12 mm, the auxiliary gas-tight seal will be fitted to the trocar
tube immediately after the trocar has been removed from the trocar
tube, and will remain attached to the trocar tube throughout the
rest of the procedure. Only if the trocar were reinserted into the
trocar tube, or if some other unprotected sharp instrument were
inserted into the trocar tube, would the auxiliary gas-tight seal
have to be removed to prevent the trocar or sharp instrument from
cutting the instrument seal 32.
The preferred embodiment of the auxiliary gas-tight seal according
to the invention will next be described, together with some
variations on the preferred embodiment. Testing of the auxiliary
gas-tight seal shown in FIGS. 1 through 4C showed good results with
most types of instruments having a wide range of diameters. Testing
showed, however, that a large-diameter instrument with a pronged
distal end, such as certain types of clip applier, would penetrate
the flat instrument seal 32 at points remote from the instrument
port 38 instead of entering the instrument port and stretching the
material of the instrument seal surrounding the instrument port.
Penetration of the instrument seal reduces the effectiveness of the
seal. Testing also showed that a further increase in lateral
compliance was desirable. Finally, production considerations made
it desirable to find a better way of attaching the stabilizing
-ting halves 44A and 44B to one another than by the pins 46.
A cross sectional view of the preferred embodiment of the auxiliary
gas-tight seal 10B according to the invention is shown in FIG. 5A.
Components that correspond to components shown in FIGS. 1 through
4C use the same reference number with the letter "B" added. A
cross-sectional exploded view of the seal molding 40B, the base
60B, the cap 66B and the stabilizing ring halves 44AB and 44BB are
shown in FIG. 5B. A plan and cross sectional view of a stabilizing
ting half are shown in FIGS. 5C and 5D, respectively.
Referring to these drawings, the seal molding 40B retains the four
zones, namely, the instrument seal 32B, the stabilizing ting anchor
50B, the corrugated zone 52B, and the anchoring ring 42B, described
above. 0f these, the stabilizing ring anchor and the anchoring ting
are unchanged, and so will not be further described.
The instrument seal 32B has a distally-extending conical shape
centered on the instrument port 38B. The revised shape of the
instrument seal 32B reduces the ability of an instrument with a
pronged distal end to penetrate the instrument seal by generating a
lateral component from the force between the instrument and the
instrument seal. The lateral component laterally displaces the
material surrounding the instrument port and enables the pronged
end of the instrument to enter the instrument port. In other words,
the pronged end of the instrument is guided up the conical sides of
the instrument seal and enters the instrument port.
The included angle of the conical instrument seal 32B is in the
range of 60 to 120 degrees. Reducing the angle increases the
ability of the instrument seal to resist penetration, but increases
friction between the instrument and the seal. The current preferred
angle is 75 degrees. The thickness of the conical instrument seal
32B is in the range of 0.02" to 0.06" (0.51-1.52 mm), with a
preferred thickness of 0.03" (0.76 mm).
The preferred material of the seal molding 48B is silicone rubber.
Silicone rubber has excellent rebound, i.e., ability to recover
after deformation, but a less good ability to resist penetration.
Polyurethane is an alternative material for the seal molding: the
penetration resistance of polyurethane is superior to that of
silicone rubber, but its rebound is inferior.
Using both silicone rubber and polyurethane in the instrument seal,
as shown in FIG. 6A, would offer the advantages of both materials.
The seal molding 48C would be of silicone rubber with the conical
instrument seal part 32X of the molding about 0.02" (0.5 mm) thick.
The internal (instrument contacting) part 32Y of the instrument
seal 32C would be formed of polyurethane about 0.005" (0.12 mm)
thick, attached to the instrument seal part of the seal
molding.
At least the instrument seal 32B of the seal molding 48B is coated
with an anti-friction coating, as described above.
The corrugated zone 52 shown in FIGS. 1 through 4C uses a folded
arrangement accommodated within the overall height of the
stabilizing ring 44. In the embodiment shown in FIGS. 5A and 5B,
the lateral compliance of the corrugated zone 52B has been
increased by forming the corrugated zone from a series of
substantially vertical elements 51, 53, 55, interconnected by
substantially semicircular sections 57, 59, 61. Compliance is
further increased by making the vertical elements 51, 53, 55
substantially longer than the sloped elements of the corrugated
zone 52 shown in FIG. 3A. This results in the auxiliary gas-tight
seal 10B being considerably taller than the seal auxiliary
gas-tight seal 10 shown in FIGS. 1 through 4C. In the arrangement
shown in FIGS. 5A and 5B, the material of the corrugated zone 52B
bends and/or buckles to accommodate the lateral movement of the
instrument seal 32B and stabilizing ring 44B. This requires
considerably less force than stretching the material of the
corrugated zone.
The preferred thickness of the corrugated zone 52B, at 0.01" (0.25
mm), is little changed from that of the corrugated zone 52 shown in
FIG. 3A.
The base 60B is changed to accommodate the greater height of the
corrugated zone 52B and to allow the conical instrument seal 32B to
move laterally. The thickness of the base is increased. The face
70B occupies a relatively small fraction of the area of the base,
and is surrounded by the annular pocket 63 that accommodates the
corrugated zone 52B.
Compared with the bore 72 of the base 60 shown in FIGS. 1 through
4C, the diameter of the bore 72B shown in FIGS. 5A and 5B is
increased. This is necessary because the bore must accommodate not
only the instrument, it must also accommodate the instrument seal
32B, and the maximum lateral excursion of the instrument seal. To
provide the necessary diameter of the bore, and to provide an
adequate area on the plane sealing face 76B, the bore is tapered
towards the plane sealing face 76B as shown.
The arrangement of the lugs 74B and the plane sealing face 76B for
attaching the auxiliary gas-tight seal 10B to the rear housing of
the trocar tube is unchanged from that described above, and so will
not be described further.
The cap 66B is similar to the cap 60 shown in FIG. 3A, except that
its height is increased to accommodate the increased height of the
corrugated zone 58B and the cap 60B. The cap is formed with two
internal circumferential steps 64B and 80B. The anchoring ring is
located in the annular groove formed between the outer face 58B of
the outer wall 65 of the annular pocket 63, the annular part 67 of
the base 60B outside the wall 65, and the circumferential step 64B
in the cap. The annular groove locates and forms a gas-tight seal
with the anchoring ting 42B. The part 67 of the base fits into the
circumferential step 80B and defines the relative axial location of
the base and the cap. This, in turn, defines the compression of the
anchoring ring 42B, and the distance between the faces 70B and
78B.
The stabilizing ring 44B is formed of two identical stabilizing
ring halves 44AB and 44BB, as shown in FIGS. 5A and 5B. One of the
stabilizing ring halves 44AB is shown in plan and in cross section
in FIGS. 5C and 5D, respectively. Each stabilizing ring half is an
annular plastic ring half molding 71. Formed in one plane face of
the molding is the annular groove 73 that accommodates the
stabilizing ring anchor 50B of the seal molding 48B. In four
equally-spaced locations in the annular groove are formed the pins
75, and in four equally-spaced locations, spaced equally between
the pins 75, are formed the pin holes 77. Eight equally-spaced pin
holes 79 are also formed in the stabilizing ring anchor in the seal
molding 48B.
The two stabilizing ring halves 44AB and 44BB are attached to the
seal molding 48B simply by inverting, and rotating through 45
degrees, one ring half molding 71 relative to the other. The ring
half pins 75 are then inserted through the pin holes 79 in the seal
molding, and are pressed into the pin holes 77 in the other ring
half, where they are retained by friction.
As shown in FIGS. 6B and 6C, the thickness of instrument seal 32D
and 32E, respectively, may be radially varied to provide a better
relationship between penetration resistance and friction between
the instrument seal and the instrument. FIG. 6B shows the thickness
of the instrument seal 32D decreasing with distance from the center
of the instrument port 38D. FIG. 6C shows the thickness of the
instrument seal 32E increasing with distance from the center of the
instrument port 38E. Alternatively, the thickness of the instrument
seal may be radially varied in steps to facilitate stretching of
the instrument seal and to reduce friction between the instrument
seal and the instrument. As a further alternative, the
instrument-contacting surface of the instrument may be formed with
flutes extending from the instrument port to the stabilizing ring
anchor, or with a textured, marbled, or matt finish. Finally,
scales, or cut-resistant elements, such as overlapping polyurethane
scales, may be mechanically attached to, bonded to, or formed in
the instrument-contacting surface of the instrument seal to
increase the penetration resistance of the surface and to reduce
friction between the instrument seal and the instrument.
It is further envisaged that, by using a technique such as finite
element analysis, the basic conical shape of the instrument seal
32B and its thickness could be varied to provide an optimum
relationship between penetration resistance and friction between
the instrument seal and the instrument. With such an optimization,
the shape of the instrument seal would be more complex than the
simple conical shape shown, for example, in FIGS. 5A and 5B.
Moreover, the radial variation of thickness would be more complex
than the simple linear taper shown in FIGS. 6B and 6C.
Thickness tapering may also be applied to the flat instrument seal,
as shown in FIG. 6D. In this, the flat instrument seal 32F has a
thickness of about 0.06" (1.5 mm) at its outer periphery, adjacent
to the stabilizing ring anchor 50F. The thickness gradually tapers
to about 0.035" (0.9 mm) at the periphery of the instrument port
38F.
The thickness of the instrument seal may also be selectively
reduced adjacent to the instrument port, as shown in FIG. 6E. In
this, the instrument seal 32G has a thickness of about 0.06" (1.5
mm) at its outer periphery, adjacent to the stabilizing ting anchor
50G. The thickness is reduced to about 0.04" (1 mm) in an annular
area 81 surrounding the instrument port 38. The annular area has an
outside diameter of about 0.12" (3 mm).
FIG. 7 shows an alternative embodiment in which the corrugated
section 52C of the seal molding 48C extends proximally instead of
distally. The seal molding also includes the conical instrument
seal 32C. To accommodate the proximally-extending corrugated
section, the base 60C and the cap 66C are changed. The base 60C
retains the large internal face 70C of the arrangement shown in
FIG. 3A. The plane face 70C terminates in the peripheral wall 65C.
The bore 72C has a large diameter to accommodate the instrument,
the conical instrument seal, and the lateral movement of the
instrument seal. The cap 66C has the internal face 78C that
occupies a small part of the area of the cap, and is surrounded by
the annular pocket 83 that accommodates the corrugated zone 52C.
The bore 82C is flared towards the plane face 78C. In this
embodiment, the tunnel between the proximal face 85 of the cap and
the instrument port 38C at the distal end of the instrument seal
guide the instrument towards the center of the instrument port and
facilitate passage of the instrument through the instrument
port.
The features described above with respect to FIGS. 5A through 7 may
also be selectively included in the embodiment shown in FIGS. 1
through 4C.
An alternative embodiment of the auxiliary gas-tight seal according
to the invention is shown in FIG. 8. In this embodiment, which is
based on the embodiment shown in FIGS. 1 through 4C, parts that are
similar to those in the preferred embodiment shown in FIGS. 3A and
3B are numbered with the same reference numbers with 100 added. In
the alternative embodiment shown in FIG. 8, a different
configuration of the seal mounting is used; the instrument seal 132
and the seal mounting 134 are provided using separate components;
and the shapes of the cap 166 and the base 160 constituting the
seal body 130 are changed.
The instrument seal 132 is similar to the instrument seal 32 shown
in FIGS. 3A and 3B, and is molded of an elastic material, such as
silicone rubber, with the stabilizing ring anchor 150 as its outer
periphery. The instrument seal includes the instrument port
138.
The seal mounting 134 includes the stabilizing ring 144, the
stabilizing ring anchor 150, and the corrugated seal 121. The
stabilizing ring 144 includes the stabilizing ring halves 123 and
125, which mate with the stabilizing ring anchor 150. The
stabilizing ring half 123 is similar to the stabilizing ring halves
44A and 44B shown in FIGS. 3A and 3B, but its outer curved face 127
is changed because there is no seal molding to pass through it. The
stabilizing ring half 125 is substantially changed relative to the
stabilizing ring half 44B. The plane face 129 of the stabilizing
ring half 125 is extended radially inwards toward the instrument
port 138, and then is extended axially away from the instrument
seal 132 to form the lip 131. The lip 131 defines the periphery of
a bore 133 which has a diameter about 50% greater than the diameter
of the bore 164 in the cap 166.
The corrugated seal 121 is a molding of an elastic material, for
example, silicone rubber. The corrugated seal includes an inner
anchoring ring 137 and an outer anchoring ring 139 interconnected
by a corrugated section 141. The anchoring rings are preferably
thicker than the corrugated section.
The inner anchoring ring 137 is adapted for attaching to the lip
133 by means of a suitable adhesive, a metal or plastic clamp (not
shown), or some other suitable means. The outer anchoring ring 139
is adapted for attaching to the base 160 by means of a suitable
adhesive, a metal or plastic clamp (not shown), or some other
suitable means. Alternatively, the outer anchoring ring can be
compressed in an annular groove (not shown) formed between a step
on the base 160 and a corresponding step on a suitable annular
sleeve (not shown) fitting inside the base similar to the way in
which the base fits inside the cap in FIGS. 3A and 3B.
The alternative embodiment shown in FIG. 8 operates similarly to
the preferred embodiment described with reference to FIGS. 3A and
3B. The instrument seal 132 is free to move laterally between the
cap 166 and the base 160. This allows the excess radial force
between the instrument seal 132 and the instrument to be reduced,
which, in turn, reduces friction between the instrument seal 132
and an instrument having a diameter at the maximum of the range of
diameters. Thus, the seal can accommodate a greater range of
instrument diameters without leaking and without excessive
friction.
The stabilizing ring 144 isolates the instrument seal 132 from the
seal mounting 134, as before, and also transfers axial forces
directly from the instrument seal 132 to the seal body 130,
comprising the cap 166 and the base 160.
The seal mounting 134 is laterally compliant while providing a
gas-fight seal between the seal body 130 and the instrument seal
132. To move the instrument seal 132 laterally requires that the
instrument exert relatively little radial force on the instrument
port 138.
A conical instrument seal, similar to that shown in FIG. 5A, may be
substituted for the flat instrument seal 132.
In a further alternative embodiment, shown in FIG. 9, the
corrugated seal 141 shown in FIG. 8, and the planar corrugated seal
52 shown in FIGS. 3A and 3B are dispensed with, and the
laterally-compliant seal is provided by a sliding seal between the
stabilizing ring and the seal body.
In FIG. 9, parts that are similar to the embodiments shown in FIGS.
3A and 3B, and FIG. 8 are numbered with the same reference numbers
with 100 or 200, respectively, added. The base 260 and the cap 266
are similar to the base 60 and the cap 66 shown in FIGS. 3A and 3B,
except that no provision is made for mounting the anchoring ring 42
(FIGS. 3A and 3B). The instrument seal 232 is similar to the
instrument seal 132 shown in FIG. 8. As in FIG. 8, the instrument
seal 232 is molded with the stabilizing ring anchor 250 at its
periphery.
The stabilizing ring anchor 250 mates with the stabilizing ring
halves 251 and 253, respectively. Both stabilizing ring halves 251
and 253 are similar to the stabilizing ring half 123 shown in FIG.
8, but the plane face of each stabilizing ring half is modified to
include the projecting annular wiper 255 and 257, respectively.
Alternatively, a groove can be formed in the flat surface of each
stabilizing ting half, and an annular wiper of a different material
can be affixed into the groove.
The wiper 255 contacts internal face 278 of the cap 266. The wiper
257 contacts the internal face 270 of the base 260. Contact between
the wiper 257 and the internal face 270 forms a primary sliding
gas-tight seal. Contact between the upper wiper 255 and the
internal face 278 forms a secondary gas-tight seal that seals any
gas that escapes past the primary sliding gas-tight seal.
The axially-opposed primary and secondary gas-tight seals require a
relatively small axial force between the wipers and their
respective internal faces to provide an effective gas-tight seal.
This seal remains gas-tight when an axial load is imposed on the
seal, such as that imposed when an instrument is inserted or
withdrawn, despite the small force between the wipers and their
respective sealing faces. It is desirable to have a relatively
small force between the wipers and their respective sealing
surfaces to minimize friction, and thus maximize the lateral
compliance of the instrument seal 232. Friction can be further
reduced by coating the wipers 255 and 257 and the internal faces
270 and 278 with a suitable anti-friction layer.
Withdrawing an instrument from the instrument port 238 tends to
move the stabilizing ring 244 away from the base 260, which tends
to break the primary gas-tight seal. However, in moving away from
the base 260, the stabilizing ring 244 moves towards the cap 266.
This increases the contact force between the wiper 255 and the
internal face 270, and strengthens the secondary gas-tight seal. On
the other hand, inserting an instrument into the instrument port
tends to move the stabilizing ring 244 towards the base 260, which
strengthens the primary gas-tight seal.
A conical instrument seal, similar to that shown in FIG. 5A, may be
substituted for the flat instrument seal 232.
FIG. 10 shows a simplified version of the arrangement shown in FIG.
9 in which the wipers are omitted from the stabilizing ting 344.
Parts similar to parts shown in FIG. 9 are numbered with the same
reference numbers with 100 added. In this embodiment, the internal
faces 370 and 378, the mating surfaces of the cap 366 and the base
360, and the plane surfaces of the stabilizing ting 344 are formed
with sufficient precision that the gap between the plane faces of
the stabilizing ring and the respective internal faces of the cap
and the base is of the order of 25 .mu.m (0.001"). This dimension
is large enough to allow the stabilizing ting to slide freely
between the cap and the base. Gas pressure acting on the instrument
seal 332 moves the plane surface 365 of the stabilizing ting half
323 into contact with the internal face 378. This forms a gas-tight
seal between the plane surface 365 and the internal face 378.
Inserting an instrument into the instrument port 338 may break this
seal, but forces the plane face 367 of the stabilizing ting haft
326 into contact with the internal face 370. This forms a gas-tight
seal between the plane surface 367 and the internal face 370.
A conical instrument seal, similar to that shown in FIG. 5A, may be
substituted for the flat instrument seal 332.
The radial force between the instrument seal 32 (FIG. 3A) and the
instrument can be further reduced by transmitting directly from the
instrument to the stabilizing ring the lateral force required to
move the seal mounting 34 laterally. This relieves the instrument
seal of the task of transmitting this lateral force, which enables
the radial force between the instrument seal and a minimum-diameter
instrument to be further reduced. Reducing the radial force between
the instrument seal and a minimum-diameter instrument increases the
range of instrument diameters that the seal can accommodate.
A number of arrangements which include a lateral force transmitting
mechanism to transmit directly from the instrument to the
stabilizing ring 44 the force required to move the seal mounting
laterally will now be described. FIGS. 11A-11C, 12A, 12B, 13, 14A
and 14B only show the stabilizing ring 444 and the instrument seal
432. The lateral force transmitting mechanism embodiments shown in
these Figures and in FIGS. 15A and 15B may be applied to any of the
embodiments and variations shown in FIGS. 3A and 3B, 5A, 5B, 6A
through 6E, 7, 8, 9, and 10, all of which include a stabilizing
ring and an instrument seal.
In the simple embodiment of the lateral force transmitting
mechanism shown in FIGS. 11A through 11C, the thickness of one of
the stabilizing ring halves comprising the stabilizing ring 444 is
increased to accommodate the lateral force transmitting mechanism.
In the simple lateral force transmitting mechanism, the increase in
the thickness of the stabilizing ring half 423 is relatively small
because the simple lateral force transmitting mechanism has a
relatively low profile. The more complex lateral force transmitting
mechanisms shown in FIGS. 12A and 12B, 13, and 14A and 14B require
a greater increase in the thickness of the stabilizing ting half
423.
In the simple lateral force transmitting mechanism shown in FIGS.
11A through 11C, three wire springs 469, 471, and 473 are attached
in a radially-symmetrical arrangement to the stabilizing ting half
423. The wire springs are radially offset so that they are
substantially tangential to the instrument port 438. The parts of
the wire springs adjacent to the instrument port 438 may overlap
one another as shown. This may be achieved by appropriately bending
each wire spring, or by mounting each wire spring at a different
point in the thickness of the stabilizing ting, as shown in FIG.
11B.
With the lateral force transmitting mechanism shown, the wire
springs 469, 471, and 473 are biased into contact the instrument,
such as the instrument I, inserted into the instrument port 438.
The wire springs exert a radial compressive force against the
instrument. The compressive force is as radially symmetrical as is
possible with a radial force applied by three discrete elements.
The compressive force can be made more symmetrical at the expense
of greater complexity by increasing the number of wire springs.
When the instrument I is moved laterally, the instrument applies a
lateral force to one or more of the wire springs 469, 471, and 473.
Each wire spring to which the lateral force is applied transmits
the lateral force directly to the stabilizing ring 444. The lateral
force thus applied directly to the stabilizing ring moves the
stabilizing ting and the instrument seal 432 laterally with the
lateral movement of the instrument. In this way, the lateral force
transmitting mechanism moves the instrument seal laterally and
considerably reduces the force between the instrument seal and the
instrument required to move the instrument seal laterally.
The elasticity of the wire springs 469, 471, and 473 enables the
wire springs to move radially when a larger-diameter instrument,
such as the instrument I' shown in FIG. 11C, is inserted into the
instrument port.
Like the instrument seal 432, the wire springs 469,471, and 473
exert a radial force against the instrument. This radial force
increases with increasing diameter of the instrument. However,
friction on the instrument resulting from the radial force exerted
by the wire springs is less than that resulting from the radial
force exerted by the instrument seal because the coefficient of
friction between the wire springs and the instrument is less than
that between the instrument seal and the instrument.
The parts of the wire springs 469,471, and 473 remote from the
stabilizing ring 444 may be fitted with suitably-shaped paddles to
make inserting the instrument easier. Inserting the instrument may
be made even easier by fitting each wire spring with a roller, as
shown in FIGS. 12A and 12B. Each of the wire springs 469, 471, and
473 is fitted with a roller 475, 477, and 479, respectively. Each
roller is free to rotate on its respective wire spring, and is
axially located on the wire spring by bushes, or some other
suitable device. The bushes 481 and 483 are shown retaining the
roller 477 on the wire spring 471, for example.
The radial force applied to the instrument by the lateral force
transmitting mechanism can be made less dependent on the instrument
diameter increases by making the wire springs longer, as shown in
FIG. 13. In FIG. 13, the wire springs 469A, 471A, and 473A are
curved, which enables their length to be increased within the
confines of the stabilizing ring 444. In this embodiment, the
rollers 475,477, and 479 can be omitted, or can be replaced by
paddles, if desired.
In the embodiment shown in FIGS. 14A and 14B, the rollers 475, 477,
and 479 are mounted on the axles 485,487, and 490, respectively.
The axles 485,487, and 489 swivel on the pins 49 1,493, and 495
mounted on the stabilizing ting 444. A hairspring arrangement 495
biases each pivoted axle towards the instrument port 438. Such an
arrangement makes the radial force applied to the instrument by the
lateral force transmitting mechanism less dependent on the
instrument diameter. When an instrument, such as the instrument I,
is inserted into the instrument port 438, the rollers are forced
outwards, as shown in FIG. 14B, but the long effective length of
the hairspring arrangement makes the radial force between the
rollers and the instrument relatively independent of the diameter
of the instrument.
A conical instrument seal, similar to that shown in FIG. 5A, may be
substituted for the flat instrument seal 432.
FIGS. 15A and 15B show an arrangement of spring-loaded bumpers.
Each of the four bumpers 511, 513, 5 15, and 517 is mounted on a
compression spring 519, 521,523, and 525 inside the stabilizing
ring 544. This arrangement exerts a radial compressive force
against an instrument inserted into the instrument port 538. When
the instrument is moved laterally, the bumpers and springs transmit
a lateral force directly to the stabilizing ting 544. This moves
the instrument seal 532 laterally, and considerably reduces the
force between the instrument seal and the instrument required to
move the instrument seal laterally.
A conical instrument seal and a corrugated section, similar to
those shown in FIG. 5A, may be substituted for the flat instrument
seal 532, and the corrugated section 552.
Although illustrative embodiments of the invention have been
described herein in detail, it is to be understood that the
invention is not limited to the precise embodiments described, and
that various modifications may be practiced within the scope of the
invention defined by the appended claims.
* * * * *